-
Now Playing: CDC releases new report on pregnant women and COVID-19
-
Now Playing: America on high alert as inauguration approaches
-
Now Playing: Arrest made in the killing of a recent college graduate
-
Now Playing: Threat levels raised in all 50 state capitals
-
Now Playing: Green zone perimeter established in Washington, DC
-
Now Playing: Surfers enjoy big waves in Hawaii
-
Now Playing: Biden prepares for historic inauguration amid growing pandemic, protests
-
Now Playing: States enact their own security in preparation for pro-Trump demonstrations
-
Now Playing: Quarterback face-off with Tom Brady, Drew Brees
-
Now Playing: Online users leave traditional social media for encrypted apps
-
Now Playing: COVID-19 number of deaths close to 400,000
-
Now Playing: Pennsylvania Lt. Governor speaks about heightened security in the state
-
Now Playing: Manhunt underway after shooting of recent college graduate
-
Now Playing: Fatal police shooting under investigation in Texas
-
Now Playing: Biden braces to take on COVID-19 emergency
-
Now Playing: Officer recounts 'medieval battle' against Capitol mob
-
Now Playing: Biden picks Alondra Nelson as deputy science policy chief
-
Now Playing: Biden adds science adviser to Cabinet
-
Now Playing: Biden reveals key members of science team
-
Now Playing: Zoo welcomes birth of Francois’ leaf monkey